Antipodal demodulation method and antipodal demodulator for non-coherent unitary space-time modulation in MIMO wireless communication

ABSTRACT

Provided is an antipodal demodulation method and an antipodal demodulator for non-coherent unitary space-time modulation in MIMO wireless communication. The invention comprises: traversing L/2 constellation points in each sub-constellation of a non-coherent unitary space-time diagram for maximum likelihood demodulation calculation, determining a maximum trace ψ max  and a minimum trace ψ min  from traces of L/2 matrix products, calculating a maximum trace  ψ   max  of a matrix product corresponding to the constellation matrix in the other sub-constellation according to  ψ   max =tr(Y H   Φ   j   Φ   h   H Y)=tr(Y H Y)−tr(Y H Φ j Φ j   H Y)=σ−ψ min , and outputting a constellation point corresponding to the greater one of ψ max  and  ψ   max  as a demodulation signal. The antipodal demodulation method of the invention reduces calculation workload by ½ and features lower calculation complexity over the conventional maximum likelihood demodulation method without degrading demodulation performance.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119 and the Paris Convention Treaty, thisapplication claims the benefit of Chinese Patent Application No.201310409889.4 filed on Sep. 10, 2013, the contents of which areincorporated herein by reference.

FIELD

The invention relates to the communication technology field, and moreparticularly to an antipodal demodulation method and an antipodaldemodulator for non-coherent unitary space-time modulation in MIMOwireless communication.

BACKGROUND

With fast development of wireless communication, it has become a coreproblem for next generation wireless communication systems to increasedata transmission speeds without degrading the quality of service (QoS).Since Telatar found that multiple-input multiple-output (MIMO) systemsare capable of linearly increasing channel capacity in 1995, researchfever on wireless MIMO communication systems has been activated, and theMIMO technology has become a key technology in the next generationwireless communication systems. In addition, space-time codes are one ofthe main transmission technologies for long-term evolution (LTE) of thethird-generation (3G) communication.

The MIMO communication system is divided into a coherent communicationsystem and a non-coherent communication system based on requirement forchannel estimation during demodulation. The non-coherent space-time codeis divided into a differential space-time code and a unitary space-timecode, and this invention is aimed at the unitary space-time code sincethere is very little research achievement for non-coherent unitaryspace-time demodulation methods. At present, experimental simulationplatforms for designing the non-coherent space-time code mainly use amaximum likelihood algorithm as a demodulation algorithm. Maximumlikelihood demodulation comprises calculating likelihood probabilitiesof all constellation points, and selecting a constellation point withthe greatest likelihood probability as an output signal of ademodulator. However, a problem with the demodulation method traversingall the constellation points is that, calculation workload andcomplexity linearly increase as a constellation becomes larger.

SUMMARY

It is an objective of the invention to provide an antipodal demodulationmethod for non-coherent unitary space-time modulation in MIMO wirelesscommunication, the method finds an antipodal structure of ahigh-performance unitary space-time constellation and relationshipbetween different antipodes by analyzing conventional non-coherentunitary space-time diagrams, and features the same demodulationperformance as a maximum likelihood demodulation method with the numberof constellation points half of that thereof during a demodulationprocess.

Provided is an antipodal demodulation method for non-coherent unitaryspace-time modulation in MIMO wireless communication, comprising stepsof:

(1) dividing an antipode-based unitary space-time constellation

C₁ = {Φ_(l)}_(l = 1)^(L)into two sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)and

${{\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}},$where L represents the number of constellation points in theconstellation, Φ_(l) and Φ _(l) represents two T×M complex matrices, Trepresents a coherent time interval, M represents the number oftransmission antennas, Φ_(αβ) and Φ _(αβ) represents signals transmittedby the β^(th) transmission antenna at time α, there is no antipode pairin the sub-constellation, and there is one-to-one correspondence betweentwo antipodes in different sub-constellations;

(2) obtaining traces of a matrix product of L/2 constellation matricesin the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)and a receiving signal matrix Y: ψ_(l)=tr(Y^(H)Φ_(l)Φ_(l) ^(H)Y), l=1,2,. . . L/2, determining a maximum trace ψ_(max) and a minimum traceψ_(min) therefrom, calculating the trace of a matrix product of saidreceiving signal matrix Y: σ=tr(Y^(H)Y), and corresponding constellationmatrices Φ_(i) and Φ_(j) in the sub-constellation C₁={Φ_(l)}_(l=1)^(L/2) according to the maximum trace ψ_(max) and the minimum traceψ_(min), obtaining an antipode matrix Φ _(j) antipodal to Φ_(j) inanother sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$according to relationship between the antipodes, calculating a maximumtrace ψ _(max) of a matrix product corresponding to the othersub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$according to a relationship among the constellation matrices Φ_(j) and Φ_(j) antipodal to each other, and the receiving signal matrix Y: ψ_(max)=σ−ψ_(min)=tr(Y^(H) Φ _(j) Φ _(j)^(H)Y)=tr(Y^(H)Y)−tr(Y^(H)Φ_(j)Φ_(j) ^(H)Y), where the receiving signalmatrix Y represents a T×N complex matrix, T represents a coherent timeinterval, N represents the number of receiving antennas, y_(αγ)represents a signal received by the γ^(th) receiving antenna at the timeα, and tr(□) represents obtaining a trace of a matrix within thebrackets; and

(3) comparing the maximum trace ψ_(max) and the maximum trace ψ _(max)corresponding to constellation points in the sub-constellations,determining a greater one therefrom, and selecting a constellationmatrix corresponding thereto as a demodulation signal matrix, namely,selecting the transmission signal matrix Φ_(i) corresponding to ψ_(max)from the sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$as a demodulated constellation matrix {circumflex over (ψ)}=Φ_(i) asψ_(max)> ψ _(max), and selecting the transmission signal matrix Φ _(j)corresponding to ψ _(max) from the sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$as a demodulated constellation matrix {circumflex over (Φ)}= Φ _(j) asψ_(max)< ψ _(max).

The invention uses a method of dividing the antipodal sub-constellation:firstly, the non-coherent unitary space-time constellation is dividedinto two antipodal sub-constellations, there is no antipode pair in eachsub-constellation, and there is one-to-one correspondence between twoconstellation points in different sub-constellations, then relationshipbetween antipodal constellation points during the demodulation processis determined tr(Y^(H)ΦΦ^(H)Y)+tr(Y^(H) Φ Φ ^(H)Y)=tr(Y^(H)Y), afterthat, the maximum value ψ_(max) and the minimum value ψ_(min) therefromare determined by traversing all constellation points in (one of) thesub-constellation, then the maximum trace ψ _(max) of the matrix productcorresponding to the other sub-constellation is derived according to ψ_(max)=tr(Y^(H)Y)−ψ_(min), and finally, the constellation matrixcorresponding to the greater one of ψ_(max) and ψ _(max) is output asthe demodulation signal. This method reduces calculation workload by ½and features lower calculation complexity over the conventional maximumlikelihood demodulation method without degrading demodulationperformance

Provided is an antipodal demodulator for non-coherent unitary space-timemodulation in MIMO wireless communication, comprising an input buffer, aread-only memory module, a trace-calculating module, anextreme-value-calculating module, a register group, amaximum-calculating module, a comparing and selecting module, and anoutput buffer, the input buffer is configured to receive and save areceiving signal matrix Y, and to output the receiving signal matrix Yto the trace-calculating module, the receiving signal matrix Yrepresenting a T×N complex matrix, and y_(αγ) representing a signalreceived by the γ^(th) receiving antenna at time α, the read-only memorymodule is configured to save all the constellation matrices of twosub-constellations

C₁ = {Φ_(l)}_(l = 1)^(L/2)and

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$of an antipode-based unitary space-time constellation

C = {Φ_(l)}_(l = 1)^(L),where L represents the number of constellation points in theconstellation, Φ_(l) and Φ _(l) represents two T×M complex matrices, Trepresents a coherent time interval, and Φ_(αβ) and Φ _(αβ) representssignals transmitted by the β^(th) transmission antenna at the time α,the trace-calculating module is configured to receive L/2 constellationmatrices in the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)from the read-only memory module, and the receiving signal matrix Y fromthe input buffer, calculating traces ψ_(l)=tr(Y^(H)Φ_(l)Φ_(l) ^(H)Y) andσ=tr(Y^(H)Y), and transmitting L/2 traces ψ_(l) of the matrixY^(H)Φ_(l)Φ_(l) ^(H)Y to the extreme-value-calculating module, and thetrace σ of the matrix Y^(H)Y to the maximum-calculating module, where1≦l≦L/2, and tr(□) represents obtaining a trace of a matrix within thebrackets, the extreme-value-calculating module is configured to comparethe L/2 traces ψ_(l) of the matrix Y^(H)Φ_(l)Φ_(l) ^(H)Y, and to save amaximum trace ψ_(max) and a minimum trace ψ_(min) thereof, an address i1of a constellation matrix Φ_(i) corresponding to the maximum traceψ_(max) in the read-only memory module, and an address j1 of an antipodematrix Φ _(j) corresponding to the minimum trace ψ_(min) and antipodalto a constellation matrix Φ_(j) in another sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$in the read-only memory module into the register group, where 1≦l≦L/2,the maximum-calculating module is configured to receive the trace σ ofthe matrix Y^(H)Y from the trace-calculating module, and the minimumtrace ψ_(min) from the register group, to calculate ψ _(max)=σ−ψ_(min),and to save ψ _(max) into the register group, the comparing andselecting module is configured to obtain ψ_(max) and ψ _(max) from theregister group, to compare ψ_(max) with ψ _(max), and to output acontrol signal contr operating to control the register group, and anaddress of a constellation matrix corresponding to a greater one ofψ_(max) and ψ _(max) in the read-only memory module to the read-onlymemory module, the register group is configured to save ψ_(max),ψ_(min), i1, and j1 from the extreme-value-calculating module, and ψ_(max) from the maximum-calculating module, and to output an address ofa constellation matrix corresponding to the greater one of ψ_(max) and ψ_(max) in the read-only memory module to the read-only memory moduleaccording to the control signal contr output by the comparing andselecting module, whereby controlling the read-only memory module tooutput a demodulated constellation matrix to the output buffer, and theoutput buffer is configured to receive and buffer the demodulatedconstellation matrix {circumflex over (Φ)} from the read-only memorymodule.

In a class of this embodiment, the read-only memory module is configuredto save the two sub-constellations

C₁ = {Φ_(l)}_(l = 1)^(L/2)and

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$of the antipode-based unitary space-time constellation, there is noantipode pair in each sub-constellation, and there is one-to-onecorrespondence between two antipodes in different sub-constellations,the read-only memory module is configured to output L/2 constellationmatrices in the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)to the trace-calculating module, to receive the address from theregister group indicating a corresponding constellation matrix in theread-only memory module is the demodulated constellation matrix{circumflex over (Φ)}, and to output {circumflex over (Φ)} to the outputbuffer.

In a class of this embodiment, the extreme-value-calculating module isconfigured to receive L/2 traces ψ_(l) of matrices Y^(H)Φ_(l)Φ_(l) ^(H)Youtput by ψ_(l) computing units in the trace-calculating module, todetermine a maximum trace ψ_(max) and a minimum trace ψ_(min) therefrom,to output the maximum trace ψ_(max) and the minimum trace ψ_(min) to theregister group, and to output the address it of the constellation matrixΦ_(i) corresponding to the maximum trace ψ_(max) in the read-only memorymodule, and the address j1 of the antipode matrix Φ _(j) correspondingto the minimum value ψ_(min) and antipodal to the constellation matrixΦ_(j) in another sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$in the read-only memory module into the register group, where 1≦l≦L/2;

In a class of this embodiment, the maximum-calculating module isconfigured to receive the trace σ of the matrix Y^(H)Y from σ computingunit in the trace-calculating module, to obtain the minimum traceψ_(min) from the register group, to calculate ψ _(max)=σ−ψ_(min), and tooutput ψ _(max) to the register group.

In a class of this embodiment, the register group is configured toreceive and to save ψ_(max) and ψ_(min) from theextreme-value-calculating module, and the address i1 of theconstellation matrix Φ_(i) corresponding to the maximum trace ψ_(max) inthe read-only memory module, and the address j1 of the antipode matrix Φ_(j) corresponding to the minimum value ψ_(min) and antipodal to theconstellation matrix Φ_(j) in another sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$in the read-only memory module, to output ψ_(min) to themaximum-calculating module, to receive and save ψ _(max) from themaximum-calculating module, and to output ψ_(max) and ψ _(max) to thecomparing and selecting module.

In a class of this embodiment, the comparing and selecting module isconfigured to compare ψ_(max) with ψ _(max), and to output the controlsignal contr operating to control the register group to the registergroup so that the register group transmits the address i1 of theconstellation matrix Φ_(i) corresponding to the maximum trace ψ_(max) inthe read-only memory module to the read-only memory module if ψ_(max)> ψ_(max), and transmits the address j1 of the constellation matrix Φ _(j)corresponding to the maximum trace ψ _(max) in the read-only memorymodule to the read-only memory module if ψ_(max)< ψ _(max).

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 is a block diagram of an antipodal demodulator for non-coherentunitary space-time modulation in MIMO wireless communication.

SPECIFIC EMBODIMENTS

For clear understanding of the objectives, features and advantages ofthe invention, detailed description of the invention will be given belowin conjunction with accompanying drawings and specific embodiments. Itshould be noted that the embodiments are only meant to explain theinvention, and not to limit the scope of the invention.

Principle of the method of the invention will be described below:

(1) Maximum Likelihood Demodulation

Assume a MIMO wireless communication system comprises M transmissionantennas and N receiving antennas, a symbol transmission intervalthereof is T, and channel fading coefficient is constant in a cycle T,and varies in different cycles. Assume Φ represents a T×M transmissionsignal unitary matrix and a transmission symbol, Y represents a T×Nreceiving signal matrix and a receiving symbol, H is a M×N channelfading coefficient matrix, and W is a T×N additive white Gaussian noise(AWGN) matrix, and all elements in H and W are independently andidentically distributed random variables which obey the CN(0,1)distribution, wherein ρ represents a signal-noise ratio (SNR) at eachreceiving antenna, and a normalization coefficient √{square root over(ρ/M)} ensures an average signal-noise ratio of each receiving antennais ρ. A Rayleigh fast flat-fading channel model is defined as:

$\begin{matrix}{Y = {{\sqrt{\frac{\rho\; T}{M}}\Phi\; H} + W}} & (1)\end{matrix}$

Assume C={Φ_(l)}_(l=1) ^(L) represents the non-coherent unitaryspace-time diagram, tr(•) represents calculating a trace of a matrixwithin the brackets, (•)^(H) represents a complex conjugate transpose ofa matrix or a vector, p(Y|Φ_(l)) represents a conditional probability ofthe receiving symbol Y as the transmission symbol is Φ_(l), {circumflexover (Φ)} represents a demodulated constellation matrix which is alsothe signal output matrix, arg max tr( ) represents calculating traces ofall the constellation matrices and determining the maximum trace, andthen obtaining the demodulated constellation matrix {circumflex over(Φ)} corresponding to the maximum trace, where ψ_(l) represents aconditional probability or a trace of the matrix product Y^(H)Φ_(l)Φ_(l)^(H)Y. A maximum likelihood demodulation algorithm of the receiverwithout channel estimation is:

$\begin{matrix}{\left. {\hat{\Phi} = {\underset{\Phi_{l} \in C}{argmax}{p\left( Y \right.}\Phi_{l}}} \right) = {\underset{\Phi_{l} \in C}{argmax}\mspace{11mu}{{tr}\left( {Y^{H}\Phi_{l}\Phi_{l}^{H}Y} \right)}}} & (2)\end{matrix}$

Assume the trace of the matrix product Y^(H)Φ_(l)Φ_(l) ^(H)Y is:ψ_(l) =tr(Y ^(H)Φ_(l)Φ_(l) ^(H) Y)  (3)

where 1≦l≦L.

(2) Antipodal Constellation

Assume U, V represent two T×M matrices on the complex domain space(where T=2M)), Σ_(U) _(H) _(V) represents a diagonal matrix formed bysingular values of a matrix U^(H)V, d(U, V) represents a Frobenius chorddistance between U and V:d(U, V)=√{square root over (2M−2tr(Σ_(U) _(H) _(V)))}  (4)

Two points Φ_(α) and Φ_(β) with the biggest Frobenius chord distance aredefined as antipodes, and it is obvious that the Frobenius chorddistance therebetween is d(Φ_(α),Φ_(β))=√{square root over (2M)}. Theantipodal constellation is defined as follows: if the unitary space-timeconstellation comprises L/2 pairs of antipodes, this kind ofconstellation is referred to as the antipodal constellation.

(3) Relationship Between the Antipodal Constellation matrix and theReceiving Signal Matrix

For the antipodal constellation, two constellation matrix Φ and Φantipodal to each other and the receiving signal matrix Y have thefollowing relationship:tr(Y ^(H)ΦΦ^(H) Y)+tr(Y ^(H) Φ Φ ^(H) Y)=tr(Y ^(H) Y)  (5)

Assume σ represents a trace of an autocorrelation matrix Y^(H)Y of theoutput matrix Y, thenσ=tr(Y ^(H) Y)  (6)

Equation (5) can be proved as follows: Assume Φ=[φ₁ φ₂ . . . φ_(M)], Φ=[φ ₁ φ ₂ . . . φ _(M)], where Φ and Φ are an antipode pair, φ_(i) and φ_(i) are respectively T-dimensional column vectors of Φ and Φ. It can beseen from definition of the antipode that column vectors between Φ and Φare unit orthogonal to each other, namely φ_(i)⊥ φ _(i), i=1,2, . . . ,M. Two matrices orthogonal to each other satisfy

${{{\Phi\Phi}^{H} + {\overset{\_}{\Phi}{\overset{\_}{\Phi}}^{H}}} = {{\left\lbrack {\Phi\;\overset{\_}{\Phi}} \right\rbrack\begin{bmatrix}\Phi^{H} \\{\overset{\_}{\Phi}}^{H}\end{bmatrix}} = I}},$where I is a T×T unit matrix.

It can be deduced from the left part of equation (5) that:tr(Y ^(H)ΦΦ^(H) Y)+tr(Y ^(H) Φ Φ ^(H) Y)=tr(Y ^(H)(ΦΦ^(H)+ Φ Φ^(H))Y)=tr(Y ^(H) IY)=σ

(4) Antipodal Demodulation Method

An antipodal demodulation method for non-coherent unitary space-timemodulation in MIMO wireless communication of the invention comprisessteps of:

(1) dividing an antipode-based unitary space-time constellation

C = {Φ_(l)}_(l = 1)^(L)into two sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)and

${{\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}},$there is no antipode pair in each sub-constellation, and there isone-to-one correspondence between two antipodes in differentsub-constellations;

(2) using equation (3) to traverse and calculate traces of a product ofL/2 constellation matrices in the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)and a receiving signal matrix Y: ψ_(l)=tr(Y^(H)Φ_(l)Φ_(l) ^(H)Y), l=1,2,. . . L/2, determining a maximum trace ψ_(max) and a minimum traceψ_(min) therefrom, and corresponding constellation matrices Φ_(i) andΦ_(j) in the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)according to the maximum trace ψ_(max) and the minimum trace ψ_(min)respectively, obtaining an antipode matrix Φ _(j) antipodal to Φ_(j) inanother sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$according to relationship between the antipodes, calculating a maximumtrace ψ _(max) of a matrix product corresponding to the othersub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$according to a relationship among the constellation matrices Φ_(j) and Φ_(j) antipodal to each other, and the receiving signal matrix Y:ψ _(max) =tr(Y ^(H) Φ _(j) Φ _(j) ^(H) Y)=tr(Y ^(H) Y)−tr(Y^(H)Φ_(j)Φ_(j) ^(H) Y)=σ−ψ_(min)  (7);

and

(3) comparing the maximum trace ψ_(max) and the maximum trace ψ _(max)corresponding to constellation points in the sub-constellations,determining a greater one therefrom, and selecting a constellationmatrix corresponding thereto as a demodulation signal matrix, namely,selecting the transmission signal matrix Φ_(i) corresponding to ψ_(max)from the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)as a demodulated constellation matrix {circumflex over (Φ)}=Φ_(i) asψ_(max)> ψ _(max), and selecting the transmission signal matrix Φ _(j)corresponding to ψ _(max) from the sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$as a demodulated constellation matrix {circumflex over (Φ)}= Φ _(j) asψ_(max)< ψ _(max).

So far, a maximum likelihood demodulation method traversing Lconstellation points is converted to an optimized maximum likelihooddemodulation method traversing L/2 constellation points.

Based on the above-mentioned antipodal demodulation method, an antipodaldemodulator for non-coherent unitary space-time modulation in MIMOwireless communication is provided for performing optimized maximumlikelihood demodulation on the antipode-based non-coherent unitaryspace-time code, as shown in FIG. 1, the demodulator comprises an inputbuffer, a read-only memory module, a trace-calculating module, anextreme-value-calculating module, a register group, amaximum-calculating module, a comparing and selecting module, and anoutput buffer.

The input buffer is configured to receive and save a receiving signalmatrix Y, and to output the receiving signal matrix Y to thetrace-calculating module, the receiving signal matrix Y representing aT×N complex matrix, and y_(αγ) representing a signal received by theγ^(th) receiving antenna at time α, the read-only memory module isconfigured to save all the constellation matrices of twosub-constellation C₁={Φ_(l)}_(l=1) ^(L/2) and C ₁={ Φ _(l)}_(l=1) ^(L/2)of an antipode-based unitary space-time constellation

C = {Φ_(l)}_(l = 1)^(L),where L represents the number of constellation points in theconstellation, Φ_(i) and Φ _(i) represents two T×M complex matrices, Trepresents a coherent time interval, and Φ_(αβ) and Φ _(αβ) representssignals transmitted by the β^(th) transmission antenna at the time α,the trace-calculating module is configured to receive L/2 constellationmatrices in the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)from the read-only memory module, and the receiving signal matrix Y fromthe input buffer, calculating traces ψ_(l)=tr(Y^(H)Φ_(l)Φ_(l) ^(H)Y) andσ=tr(Y^(H)Y), and transmitting L/2 traces ψ_(l) of the matrixY^(H)Φ_(l)Φ_(l) ^(H)Y to the extreme-value-calculating module, and thetrace σ of the matrix Y^(H)Y to the maximum-calculating module, where1≦l≦L/2, and tr(□) represents obtaining a trace of a matrix within thebrackets, the extreme-value-calculating module is configured to comparethe L/2 traces ψ_(l) of the matrix Y^(H)Φ_(l)Φ_(l) ^(H)Y, and to save amaximum trace ψ_(max) and a minimum trace ψ_(min) thereof, an address i1of a constellation matrix Φ_(i) corresponding to the maximum traceψ_(max) in the read-only memory module, and an address j1 of an antipodematrix Φ _(j) corresponding to the minimum trace ψ_(min) and antipodalto a constellation matrix Φ_(j) in another sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$in the read-only memory module into the register group, where 1≦l≦L/2,the maximum-calculating module is configured to receive the trace σ ofthe matrix Y^(H)Y from the trace-calculating module, and the minimumtrace ψ_(min) from the register group, to calculate ψ _(max)=σ−ψ_(min),and to save ψ _(max) into the register group, the comparing andselecting module is configured to obtain ψ_(max) and ψ _(max) from theregister group, to compare ψ_(max) with ψ _(max), and to output acontrol signal contr operating to control the register group, and anaddress of a constellation matrix corresponding to a greater one ofψ_(max) and ψ _(max) in the read-only memory module to the read-onlymemory module, the register group is configured to save ψ_(max),ψ_(min), i1, and j1 from the extreme-value-calculating module, and ψ_(max) from the maximum-calculating module, and to output an address ofa constellation matrix corresponding to the greater one of ψ_(max) and ψ_(max) in the read-only memory module to the read-only memory moduleaccording to the control signal contr output by the comparing andselecting module, whereby controlling the read-only memory module tooutput a demodulated constellation matrix to the output buffer, and theoutput buffer is configured to receive and buffer the demodulatedconstellation matrix {circumflex over (Φ)} from the read-only memorymodule.

The read-only memory module is configured to save the twosub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)and

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$of the antipode-based unitary space-time constellation, there is noantipode pair in each sub-constellation, and there is one-to-onecorrespondence between two antipodes in different sub-constellations,the read-only memory module is configured to output L/2 constellationmatrices in the sub-constellation

C₁ = {Φ_(l)}_(l = 1)^(L/2)to the trace-calculating module, to receive the address from theregister group indicating a corresponding constellation matrix in theread-only memory module is the demodulated constellation matrix{circumflex over (Φ)}, and to output {circumflex over (Φ)} to the outputbuffer.

The extreme-value-calculating module is configured to receive L/2 tracesψ_(l) of matrices Y^(H)Φ_(l)Φ_(l) ^(H)Y output by ψ_(l) computing unitsin the trace-calculating module, to determine a maximum trace ψ_(max)and a minimum trace ψ_(min) therefrom, to output the maximum traceψ_(max) and the minimum trace ψ_(min) to the register group, and tooutput the address i1 of the constellation matrix Φ_(i) corresponding tothe maximum trace ψ_(max) in the read-only memory module, and theaddress j1 of the antipode matrix Φ _(j) corresponding to the minimumvalue ψ_(min) and antipodal to the constellation matrix Φ_(j) in anothersub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$in the read-only memory module into the register group, where 1≦l≦L/2;

The maximum-calculating module is configured to receive the trace a ofthe matrix Y^(H)Y from σ computing unit in the trace-calculating module,to obtain the minimum trace ψ_(min) from the register group, tocalculate ψ _(max)=σ−ψ_(min), and to output ψ _(max) to the registergroup.

The register group is configured to receive and to save ψ_(max) andψ_(min) from the extreme-value-calculating module, and the address i1 ofthe constellation matrix Φ_(i) corresponding to the maximum traceψ_(max) in the read-only memory module, and the address j1 of theantipode matrix Φ _(j) corresponding to the minimum value ψ_(min) andantipodal to the constellation matrix Φ_(j) in another sub-constellation

${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$in the read-only memory module, to output ψ_(min) to themaximum-calculating module, to receive and save ψ _(max) from themaximum-calculating module, and to output ψ_(max) and ψ _(max) to thecomparing and selecting module.

The comparing and selecting module is configured to compare ψ_(max) withψ _(max), and to output the control signal contr operating to controlthe register group to the register group so that the register grouptransmits the address i1 of the constellation matrix Φ_(i) correspondingto the maximum trace ψ_(max) in the read-only memory module to theread-only memory module if ψ_(max)> ψ _(max), and transmits the addressj1 of the constellation matrix Φ _(j) corresponding to the maximum traceψ _(max) in the read-only memory module to the read-only memory moduleif ψ_(max)< ψ _(max).

While preferred embodiments of the invention have been described above,the invention is not limited to disclosure in the embodiments and theaccompanying drawings. Any changes or modifications without departingfrom the spirit of the invention fall within the scope of the invention.

What is claimed is:
 1. An antipodal demodulation method for non-coherent unitary space-time modulation in MIMO wireless communication, comprising steps of: (1) dividing an antipode-based unitary space-time constellation C = {Φ_(l)}_(l = 1)^(L) into two sub-constellations C₁ = {Φ_(l)}_(l = 1)^(L/2) and ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ and where L represents the number of constellation points in said constellation, Φ_(l) and Φ _(l) represents two T×M complex matrices, T represents a coherent time interval, M represents the number of transmission antennas, Φ_(αβ) and Φ _(αβ) represents signals transmitted by the β^(th) transmission antenna at time α, there is no antipode pair in the sub-constellation, and there is one-to-one correspondence between two antipodes in different sub-constellations; (2) obtaining traces of a matrix product of L/2 constellation matrices in said sub-constellation C₁={Φ_(l)}_(l=1) ^(L/2) and a receiving signal matrix Y: ψ_(l)=tr(Y^(H)Φ_(l)Φ_(l) ^(H)Y), l=1,2, . . . L/2, determining a maximum trace ψ_(max) and a minimum trace ψ_(min) therefrom, calculating the trace of a matrix product of said receiving signal matrix Y: σ=tr(Y^(H)Y), and corresponding constellation matrices Φ_(i) and Φ_(j) in said sub-constellation C₁ = {Φ_(l)}_(l = 1)^(L/2) according to said maximum trace ψ_(max) and said minimum trace ψ_(min), obtaining an antipode matrix Φ _(j) antipodal to Φ_(j) in another sub-constellation ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ according to relationship between said antipodes, calculating a maximum trace ψ _(max) of a matrix product corresponding to the other sub-constellation ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right)_{l = 1}^{L/2}$ according to a relationship among said constellation matrices Φ_(j) and Φ _(j) antipodal to each other, and said receiving signal matrix Y: ψ _(max)=σ−ψ_(min)=tr(Y^(H) Φ _(j) Φ _(j) ^(H)Y)=tr(Y^(H)Y)−tr(Y^(H)Φ_(j)Φ_(j) ^(H)Y), where said receiving signal matrix Y represents a T×N complex matrix, T represents a coherent time interval, N represents the number of receiving antennas, y_(αγ) represents a signal received by the γ^(th) receiving antenna at said time α, and tr(□) represents obtaining a trace of a matrix within the brackets; and (3) comparing said maximum trace ψ_(max) and said maximum trace ψ _(max) corresponding to constellation points in said sub-constellations, determining a greater one therefrom, and selecting a constellation matrix corresponding thereto as a demodulation signal matrix, namely, selecting said transmission signal matrix Φ_(i) corresponding to ψ_(max) from said sub-constellation C₁ = {Φ_(l)}_(l = 1)^(L/2) as a demodulated constellation matrix {circumflex over (ψ)}=Φ_(i) as ψ_(max)> ψ _(max), and selecting said transmission signal matrix Φ _(j) corresponding to ψ _(max) from said sub-constellation ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ as a demodulated constellation matrix {circumflex over (Φ)}= Φ _(j) as ψ_(max)< ψ _(max).
 2. An antipodal demodulator for non-coherent unitary space-time modulation in MIMO wireless communication, comprising an input buffer, a read-only memory module, a trace-calculating module, an extreme-value-calculating module, a register group, a maximum-calculating module, a comparing and selecting module, and an output buffer, wherein said input buffer is configured to receive and save a receiving signal matrix Y, and to output said receiving signal matrix Y to said trace-calculating module, said receiving signal matrix Y representing a T×N complex matrix, and y_(αγ) representing a signal received by the γ^(th) receiving antenna at time α; said read-only memory module is configured to save all the constellation matrices of two sub-constellations C₁ = {Φ_(l)}_(l = 1)^(L/2) and ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ of an antipode-based unitary space-time constellation C = {Φ_(l)}_(l = 1)^(L), where L represents the number of constellation points in said constellation, Φ_(l) and Φ_(l) represents two T×M complex matrices, T represents a coherent time interval, and Φ_(αβ) and Φ _(αβ) represents signals transmitted by the β^(th) transmission antenna at said time α; said trace-calculating module is configured to receive L/2 constellation matrices in said sub-constellation C₁ = {Φ_(l)}_(l = 1)^(L/2) from said read-only memory module, and said receiving signal matrix Y from said input buffer, calculating traces ψ_(l)=tr(Y^(H)Φ_(l)Φ_(l) ^(H)Y) and σ=tr(Y^(H)Y), and transmitting L/2 traces ψ_(l) of said matrix Y^(H)Φ_(l)Φ_(l) ^(H)Y to said extreme-value-calculating module, and said trace σ of said matrix Y^(H)Y to said maximum-calculating module, where 1≦l≦L/2, and tr(□) represents obtaining a trace of a matrix within the brackets; said extreme-value-calculating module is configured to compare said L/2 traces ψ_(l) of said matrix Y^(H)Φ_(l)Φ_(l) ^(H)Y, and to save a maximum trace ψ_(max) and a minimum trace ψ_(min) thereof, an address i1 of a constellation matrix Φ_(i) corresponding to said maximum trace ψ_(max) in said read-only memory module, and an address j1 of an antipode matrix Φ _(j) corresponding to said minimum trace ψ_(min) and antipodal to a constellation matrix Φ_(j) in another sub-constellation ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ in said read-only memory module into said register group, where 1≦l≦L/2; said maximum-calculating module is configured to receive said trace σ of said matrix Y^(H)Y from said trace-calculating module, and said minimum trace ψ_(min) from said register group, to calculate ψ _(max)=σ−ψ_(min), and to save ψ _(max) into said register group; said comparing and selecting module is configured to obtain ψ_(max) and ψ _(max) from said register group, to compare ψ_(max) and ψ _(max), and to output a control signal contr operating to control said register group, and an address of a constellation matrix corresponding to a greater one of ψ_(max) and ψ _(max) in said read-only memory module to said read-only memory module; said register group is configured to save ψ_(max), ψ_(min), i1, and j1 from said extreme-value-calculating module, and ψ _(max) from said maximum-calculating module, and to output an address of a constellation matrix corresponding to said greater one of ψ_(max) and ψ _(max) in said read-only memory module to said read-only memory module according to said control signal contr output by said comparing and selecting module, whereby controlling said read-only memory module to output a demodulated constellation matrix to said output buffer; and said output buffer is configured to receive and buffer said demodulated constellation matrix {circumflex over (Φ)} from said read-only memory module.
 3. The antipodal demodulator of claim 2, wherein said read-only memory module is configured to save said two sub-constellations C₁ = {Φ_(l)}_(l = 1)^(L/2) and ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ of said antipode-based unitary space-time constellation, there is no antipode pair in each sub-constellation, and there is one-to-one correspondence between two antipodes in different sub-constellations, said read-only memory module is configured to output L/2 constellation matrices in said sub-constellation C₁ = {Φ_(l)}_(l = 1)^(L/2) to said trace-calculating module, to receive said address from said register group indicating a corresponding constellation matrix in said read-only memory module is said demodulated constellation matrix {circumflex over (Φ)}, and to output {circumflex over (Φ)} to said output buffer.
 4. The antipodal demodulator of claim 2, wherein said extreme-value-calculating module is configured to receive L/2 traces ψ_(l) of matrices Y^(H)Φ_(l)Φ_(l) ^(H)Y output by ψ_(l) computing units in said trace-calculating module, to determine a maximum trace ψ_(max) and a minimum trace ψ_(min) therefrom, to output said maximum trace ψ_(max) and said minimum trace ψ_(min) to said register group, and to output said address i1 of said constellation matrix Φ_(i) corresponding to said maximum trace ψ_(max) in said read-only memory module, and said address j1 of said antipode matrix Φ _(j) corresponding to said minimum value ψ_(min) and antipodal to said constellation matrix Φ_(j) in another sub-constellation ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ in said read-only memory module into said register group, where 1≦l≦L/2.
 5. The antipodal demodulator of claim 2, wherein said maximum-calculating module is configured to receive said trace σ of said matrix Y^(H)Y from σ computing unit in said trace-calculating module, to obtain said minimum trace ψ_(min) from said register group, to calculate ψ _(max)=σ−ψ_(min), and to output ψ _(max) to said register group.
 6. The antipodal demodulator of claim 2, wherein said register group is configured to receive and to save ψ_(max) and ψ_(min) from said extreme-value-calculating module, and said address i1 of said constellation matrix Φ_(i) corresponding to said maximum trace ψ_(max) in said read-only memory module, and said address j1 of said antipode matrix Φ _(j) corresponding to said minimum value ψ_(min) and antipodal to said constellation matrix Φ_(j) in another sub-constellation ${\overset{\_}{C}}_{1} = \left\{ {\overset{\_}{\Phi}}_{l} \right\}_{l = 1}^{L/2}$ in said read-only memory module, to output ψ_(min) to said maximum-calculating module, to receive and save ψ _(max) from said maximum-calculating module, and to output ψ_(max) and ψ _(max) to said comparing and selecting module.
 7. The antipodal demodulator of claim 2, wherein said comparing and selecting module is configured to compare ψ_(max) with ψ _(max), and to output said control signal contr operating to control said register group to said register group so that said register group transmits said address i1 of said constellation matrix Φ_(i) corresponding to said maximum trace ψ_(max) in said read-only memory module to said read-only memory module if ψ_(max)> ψ _(max), and transmits said address j1 of said constellation matrix Φ _(j) corresponding to said maximum trace ψ _(max) in said read-only memory module to said read-only memory module if ψ_(max)< ψ _(max). 